Bean Validation Integration in JPA 2 - Apache …openjpa.apache.org/artifacts/JPA 2.0 Bean Validation...Title Bean Validation Integration in JPA 2.0 Author Jeremy Bauer and Donald

Apache OpenJPAhttp://openjpa.apache.org/

July 17, 2009

Copyright © 2009, The Apache Software Foundation

Bean Validation Integration in JPA 2.0

2 Copyright © 2009, The Apache Software Foundation

Legal

● This presentation is based on Early Access levels of the following specifications:

● JSR 317: Java Persistence API 2.0 – PFD (20090313)● JSR 303: Bean Validation – PFD (1.0.CR1 20090316)

– Which require the following notice:● This is an implementation of an early-draft specification developed under the Java

Community Process (JCP) and is made available for testing and evaluation purposes only. The code is not compatible with any specification of the JCP.

● Presentation is released under the Apache Software License 2.0– Copyright © 2009, The Apache Software Foundation

– Apache and the Apache feather logo are trademarks of Apache Software Foundation.

– Authored by: Jeremy Bauer and Donald Woods


Agenda

1 - Overview of JSR-303 Bean Validation 1.02 - JSR-317 JPA 2.0 support for Bean Validation3 – OpenJPA modifications for Bean Validation4 - Concerns and Issues


1 - Overview of JSR-303 Bean Validation 1.01.1 - Bean Validation Spec1.2 – Constraint Definitions1.3 – Constraint Descriptors1.4 - Spec Required Constraints1.5 - Validation Groups1.6 - Spec Defined Exceptions


1.1 – Bean Validation Spec

● JSR-303 – JCP lead is Red Hat● Hibernate Validation 4.0 will be the RI– The PFD/1.0 CR1 was the last publicized version from

JCP website.– Current validation-api source is hosted in a public repo,

so spec updates since the PFD can be tracked.● Agimatec-Validation by agimatec GmbH on Google

Code is the only other implementation we've found.– Has not finished implementing all of the PFD items.– Does not use the TraversableResolver.


1.2 – Constraint Definitions

● A null element is considered to be valid.● Each constraint supports a List<T> ● Implementations must provide a MessageResourceBundle

with some common predefined constraint messages.● Constraints can be declared on interfaces and are cumulative– Traversable fields, traversable methods (getters only), classes

(interfaces and superclasses) and traversable associations– Uses TraversableResolver.isTraversable() to determine if a

given property should be accessed.● Constraints are not processed in any particular order


1.3 – Constraint Descriptors

● Constraints can be provided by annotation or XML– No Spec requirement for Java SE 6– META-INF/validation.xml– XML overrides annotations unless ignore-annotations is

set to false on the class descriptors– Descriptors can only be provided for a given class once

● Invalid arguments lead to a IllegalArgumentException, ConstraintDeclarationException or ValidationException

● A property can have constraints on both fields and methods


1.4 – Spec Required Constraints

● @AssertTrue/AssertFalse(Boolean value) - Boolean● @DecimalMax/DecimalMin(String value) – BigDecimal,

BigInteger, String, byte/Byte, short/Short, int/Integer, long/Long● @Digits(int integer, int fraction) - BigDecimal, BigInteger,

String, byte/Byte, short/Short, int/Integer, long/Long● @Future/Past() – Date, Calendar● @Max/Min(long value) – BigDecimal, BigInteger, String,

byte/Byte, short/Short, int/Integer, long/Long● @Null/NotNull() – Object● @Pattern(String regexp, Flag flags) - String● @Size(int min, int max) – String, Collection, Map, Array.length


1.5 – Validation Groups

● Default group includes all constraints ● Uses interfaces to define subsets of constraints● Can inherit from other groups● GroupSequence can be used to redefine the Default

group for a class● GroupSequence controls the order groups are

processed and is the only way to define constraint ordering (one constraint per group)


1.6 – Validation Exceptions

● Runtime exceptions– ConstraintViolationException – generated by the framework

(JPA2) if validation failures occur and contains the set of specific ConstraintViolation(s)

– ConstraintViolation – contains the failure details: constraint descriptor, message, class, property and value

● Compile time exceptions (annotation processor)– ConstraintDefinitionException – illegal constraint– ConstraintDeclarationException – invalid constraint argument– UnexpectedTypeException – invalid property type– GroupDefinitionException – cyclic graph, illegal override


2 - JSR-317 JPA 2.0 support for Bean Validation2.1 – Validation Overview2.2 – Integration Diagram2.3 – Validator Factory2.4 – Validation Modes2.5 – Validation Groups2.6 – Validation Exceptions


2.1 – Validation Overview

● Validation is optional. The JPA 2.0 Spec does not require a Bean Validation implementation.

● A TraversableResolver must be supplied by the persistence provider, so validation:– Does not cause unloaded attributes to be loaded (confirm

to FetchType.Lazy/Eager)– Validation cascading or embedded attributes (either

marked with @Valid) does not traverse entity associations


2.2 – Integration Diagram

javax.validation

ValidatorFactory

javax.persistence

EntityManagerFactory

javax.validation

TraversableResolver

javax.persistence

EntityManager

Events

Validation Configuration

(mode and validation groups)

Attach to

PrePersist

PreUpdate Employee(entity)

@NotNullString name

Provided or Default

javax.validation

Validator

Validate (entity)

Implicit or Explicit Validation

ManagedPreRemove

isLoaded(entity)

CreateCreate

Create

isTraverseable(entity)


2.3 – Validator Factory

● Java EE containers and Java SE applications can provide a javax.persistence.validation.factory in the EMF properties Map.

● A default instance is obtained from the Validation implementation in the classloader (if one is present) if none are supplied.


2.4 - Validation Modes

● javax.persistence.ValidationMode– Auto (default) – if a validation provider is available, then

validation should occur

– Callback – validation is required and a PersistenceException must be thrown if a provider cannot be obtained

– None – no validation should be attempted and the lack of a validation provider should not cause an exception

● Can be set per PU– <validation-mode> element in the persistence.xml– javax.persistence.validation.mode in the EMF properties Map

● EMF supplied properties will override the XML


2.5 - Validation Groups

● Defines validation groups for entity life-cycle events– javax.persistence.validation.group.pre-persist – Default

validation group called after all other PrePersist callbacks.– javax.persistence.validation.group.pre-update – Default

validation group called after all other PreUpdate callbacks.– javax.persistence.validation.group.pre-remove – Default

validation group is NOT called after all other PreRemove callbacks.


2.6 – Validation Exceptions

● javax.persistence.PersistenceException – thrown if validation mode is Callback and a provider could not be obtained

● javax.validation.ConstraintViolationException – thrown if any constraint failures occur and contains the set of javax.validation.ConstraintViolation instance(s)


3 - OpenJPA modifications for Bean Validation3.1 – Configuration Updates3.2 – Integration Diagram3.3 – LifecycleEventManager3.4 – TraversableResolver3.5 – Unit Testing


3.1 – Configuration Updates

● New configuration properties– javax.persistence.validation.factory – EMF property

– javax.persistence.validation.mode – PU or EMF property

– javax.persistence.validation.group.pre-persist – PU or EMF property and entity annotation

– javax.persistence.validation.group.pre-update – PU or EMF property and entity annotation

– javax.persistence.validation.group.pre-delete – PU or EMF property and entity annotation

– openjpa.Validator - OpenJPAConfiguration()

– openjpa.LifecycleEventManager - OpenJPAConfiguration()

● Pluggable Validator– Removes dependency on JSR-303 APIs

● Pluggable LifecycleEventManager– Loaded during EMF creation in PersistenceProviderImpl by loadValidator() just like loadAgent(), as

old invocation location in BrokerImpl was restricted to kernel classes

– Requires access to openjpa-persistence classes after all config derivations are loaded


3.2 – Integration Diagram

OpenJPAConfiguration

ValidationModeValidator Impl

Validation FactoryLifecycle Validation Groups

(Validating)LifecycleEventManager

Validation Configuration

Properties via persistence.xml or

Map on createEMF()

Broker

(Validating)LifecycleEventManager

ValidatingLifecycleEventManager

Validator

Validator(JSR-303 based)

Validation GroupsValidation Factory

Validator

TraversableResolver (JSR-303 based)

ValidatingLifecycle EventManager created if:

- ValidationMode != NONE- Validation API and factory available


3.3 – LifecycleEventManager

● Extended to provide event based Validation– ValidatingLifecycleEventManager

● Validation mode and provider availability determine whether to use standard or validating event manager– Reflection used to determine existence of JSR-303 provider

and API (through ValidationUtils) – Eliminates runtime dependency on API and provider

● Calls Validator upon lifecycle events● Interacts with validation provider agnostic interface– Allows plugging in any validation implementation which

implements OpenJPA's validation interface


3.4 – TraversableResolver

● Provided to ValidationFactory upon Validator creation● Simple interface with single isTraversable method● Primary role is to prevent loading of unloaded entities/

attributes and traversal to related entities● Spec dictates the need for a provider specific resolver to

meet loading and relationship traversal reqs.– OpenJPA will provide and register a TraversableResolver

upon Validator creation● Container vs. provider level requirements unclear


3.5 – Unit Testing

● openjpa-persistence-jdbc– Tests do not require a validation provider, but need the

geronimo-validation spec– Basic ValidationMode tests– Exception tests for mode=callback but no provider

● openjpa-integration/validation– New integration module created to test with one or more

validation providers (agimatec-validation or RI)– Tests spec defined constraints, validation groups and

validator factory usage, along with any expected exceptions


The End

Documents

Bean Validation Integration in JPA 2 - Apache …openjpa.apache.org/artifacts/JPA 2.0 Bean Validation...Title Bean Validation Integration in JPA 2.0 Author Jeremy Bauer and Donald